Sink strainer



FIG. 1 is a perspective view of a sink strainer, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof; and,

FIG. 4 is a left-side elevational view thereof, the right-side elevational view, front elevational view, and rear elevational view all being a mirror image thereof. 

I claim the ornamental design for a sink strainer, as shown and described. 